The present invention relates generally to the field of communication systems and more particularly to telecommunication systems.
As telecommunication systems continue to expand services, an emphasis is to provide greater communication data (such as voice and digital data) throughput. The need for greater communication data throughput is expected to increase substantially as more telecommunication services such as digital data transmission, facsimile, call features, and video transmission are added by subscribers. This produces a need for faster switching circuits that support greater data throughput.
Presently, switching circuits such as protocol handler voice (PHV) circuits are limited in speed by the activities performed by the PHV circuit""s core processor. Future PHV circuit packs are planned to support greater than 32 code division multiple access (CDMA) voice channels. However, based on the typical performance of current PHV circuits (such as the Lucent Technologies Inc. PHV3 circuit pack), the core processor (a Motorola Inc. MC68060 microprocessor) of these PHVs will not have enough real time to respond to the voice encoders"" (vocoders) interrupts.
Additionally, modern vocoders are programmable, thus allowing them to execute various algorithms as required by the switching circuit""s core processor such as CDMA, enhanced variable rate coding (EVRC), time division multiple access (TDMA), code excited linear prediction (CLEP), etc. There is currently no standard interface defined for vocoders using these algorithms. Thus, a need exists for a programmable solution to increase the speed and throughput of telecommunication switching circuits that interface with various types of vocoders.
In accordance with the present invention, the problem of increasing the speed and throughput of telecommunication switching circuits that interface with various types of vocoders is overcome by using an hardware assist circuit that has programmable microcode located in an external memory unit.
An example system of the invention includes an assist circuit for assisting the microprocessor, of the switching circuit, process data and a control memory unit containing programmable microcode. The assist circuit is usually an application specific integrated circuit.
Additionally, a dual port memory unit is placed between the assist circuit and the microprocessor to allow both to transfer data back and forth.